An 8-year-old girl with Williams syndrome was found to have a heart murmur. Cardiac CT demonstrated a Valsalva sinus aneurysm (VSA) of the non-coronary cuspid, with left atrium (LA) indentation, resembling the face of Cyclops on a coronal reformatted image. Williams syndrome is related to some congenital disorders with interruption of the tunica media from the aortic root to the annular fibrous ring or aortic valve. However, it rarely presents at birth. The sinus of Valsalva dilates as time goes by, due to the persistent striking force from the left ventricle (LV). However, it is silent until rupture when cardiac tamponade occurs. The typical imaging appearance of VSA is of a saccular shape and originates above the aortic root, but sometimes involves the entire sinus. Although lethal complications of VSA occur without warning, prophylactic surgical intervention remains controversial. Regular imaging follow-up is advised before complications occur.